The present invention relates to a take-up cassette for web-like media, having a motor driven take-up reel with a core that is provided with a clamping mechanism for attaching the leading edge of a media strip to the core of the reel.
In the past, non-powered scroll style cassettes were used in which the media is simply pushed into a loose spiral in a cylindrical chamber. As the media is pushed into the loose spiral, the diameter of the cylindrical chamber expands. There are several problems that exist with this type of take-up cassette. For instance, the spiral type cassettes have a limited inner diameter in which it is difficult to get a tightly wrapped roll of media, therefore the take-up capacity is limited. Also, the soft photographic emulsion coating on film types of media is prone to scratching as the advancing media slides against itself as it is being coiled within the spiral. Further, the electrically insulated properties of typical spiral material, such as plastic coated spring steel, enhance the build up of static charges on the media as it is fed into the take-up cassette. Lastly, the force required to feed the media into the take-up cassette increases as the cassette becomes full, influencing the performance characteristics of the media transport system.
Media cassettes of the motor driven type have an advantage over the above spiral type take-up cassettes, in that the media can be tightly wound on the core of a motor driven take-up reel with the result that a greater quantity of media can be fed into a comparable size cassette. Also, the layers of media do not slide against each other as they do when the media is pushed into a spiral type cassette, thus decreasing the potential for scratching and electrostatic build-up.
A problem that exists in motor driven take-up cassettes having clamping mechanisms is that it is difficult to guide the leading edge of the media into the clamping mechanism due to the inherent curvature of the media The curvature becomes increasingly pronounced as the supply roll diminishes due to a decreasing diameter upon which the media supply is originally wound. The media's leading edge may also slip out of the clamping mechanism during the first revolution of the core.
It is a general object of the invention to provide a clamping mechanism with snap-action pivotal movement.
It is a specific object of the invention to temporarily restrict rotational movement of a rotationally free core half, while rotating a driven core half towards the free core half.
It is another specific object of the invention to reduce the amount of contaminating particles in an apparatus using the snap-pivot mechanism, by reducing friction and wear between moving parts.
It is a feature of the invention to have a layer of high friction thermoplastic on the pinching surface of the clamping mechanism thereby preventing material from slipping out of the clamping mechanism.